1. Field of the Invention
The present invention relates to an image forming apparatus.
2. Description of the Related Art
An image forming apparatus having a rotary type developing device which includes multiple developers, and in which a developer is rotated to a development position of a photosensitive body to develop a latent image formed on the photosensitive body so as to form a toner image on the photosensitive body is well known (see Japanese Patent Application Laid-Open (JP-A) No. 11-295961).
Further, a structure of an image forming apparatus having an image reading unit (scanner) in which the entire image reading unit moves and retreats in order to exchange a cartridge is also well known (see, for example, JP-A Nos. 2000-224360 and 2001-034141).
FIG. 8 schematically shows an image forming apparatus 1000 having a rotary type developing device 802 in which an image reading unit 900 (scanner) is disposed at an interval to the top face of an image forming unit 800 as described in JP-A No. 11-295961. In this image forming apparatus 1000, the image reading unit 900 rotates for exchange of a cartridge (not shown) and maintenance so that it retreats from above the front side of the image forming unit 800. Meanwhile, the front side refers to the side at which a user makes operations, and the opposite side to the front side is called the rear side.
The rotary type developing device 802 is very heavy because it includes multiple developers (not shown) each having a development roll (not shown) containing a magnet roll and a toner cartridge (not shown) accommodating toner. Further, the image reading unit 900 is also very heavy because it has a manuscript base (not shown) made of thick platen glass or the like.
The center of gravity of the rotary type developing device 802 is located toward the rear side (to the left side in the drawing) of the center line X of the image forming unit 800, as indicated by a dot line Y. The center of gravity of the image reading unit 900 is also located toward the rear side of the center line X of the image forming unit 800. That is, because the centers of gravity of the rotary type developing device 802 and the image reading unit 900 are inclined toward the rear side, the overall weight balance of the image forming apparatus 1000 is poor.
Further, because the center of gravity of the image reading unit 900 moves from a dot line Z1 to a dot line Z2 as the image reading unit 900 rotates, it moves further to the rear side. That is, the rotation of the image reading unit 900 worsens the weight balance further. As a consequence, the image forming apparatus 1000 becomes unstable.
Additionally, because a force is applied in a direction of pushing the image reading unit 900 to the rear side when the image reading unit 900 is rotated (see the arrow Z in the drawing), the image forming apparatus becomes further unstable.